Mod:Hunt Research Group/control basics

control file basics

dlpoly run
temperature 600.00
ensemble nve
integrator leapfrog
steps 60000
equilibration 20000
scale 100
print 100
stack 100
stats 100
timestep 0.005
cutoff 15.000
delr 0.500
rvdw 7.600
ewald precision 1.0E-6
traj 1 10 0
job time 1000000.0
close time 1000.0
finish

The information for the control file can be found in the DL_poly user manual. The version of Dlpoly being employed here is dlpoly 2.19.

During equilibration a gross rescaling outside of the thermostat is set by scale, perhaps best not used, can be used with a restart to scale the velocities to the required temperature. Only use restart in a production run, monitor the temperature/energy for no large jumps!

cutoff is long range coloumb?? and rvdw is short range vow the cutoff, the manual is very unclear about what these are exactly, this is when long range vdw is set to zero, this generates a discontinuity as the function is cut-off, but maximum half box size, advantages to making this smaller has simulation runs faster, a minimum value 3-4 lj radius, but ideally this should be larger ... one should also set this to the same value as that for which the potential was developed!

printing options for the states, storage requirements are an issue, files can get very large, so set these 100-200 to start with. In equilibration you are just checking for equilibration for production. more important is the traj command as this stores the trajectory and will influence the rdf evaluated by outside software, water use 10 but water is dynamic has low viscosity and moves very quickly for ionic liquids use larger number say 100 or larger.